Modelling small agricultural dams dynamics into the MAELIA multi-agent platform

International audience; In France, during the three last decades farmers built numerous small dams to have alternative resources for irrigation. In water deficit situations, one major question of the debate is the cumulative effect at watershed and river basin levels of small water dams on stream flows during the low flow period. This paper presents a new modelling framework to simulate hydrology and cumulative effect of small agricultural dams at river basin level that was implemented in the multi-agent modelling and simulation MAELIA platform. This modelling framework is based on the distinction of four types of small dams: connected to groundwater; disconnected from rivers; connected to the main stream of the sub-watershed; connected to secondary streams of the sub-watershed. It allows to simulate dynamic filling, discharge and emptying of each agricultural dam. It is simple and robust enough to represent individual behaviour of thousands of dams at regional scale. When implemented in integrated modelling platform like MAELIA, it allows to explore the potential cumulative impact of agricultural dams on the river and stream flow. First simulations show no significant impacts on the case-study river flow that is strongly determined by water release from big public dams. However, they show potential significant impacts in watersheds where the flow of the main stream is not influenced by release of public dams.